Biotransformation optimization of betulin into betulinic acid production catalysed by cultured Armillaria luteo-virens Sacc ZJUQH100-6 cells

Abstract

Aims: Betulinic acid has attracted attention in terms of its important biological and pharmacological characteristics. The main objective of this work was to optimize the variables of biotransformation process in order to enhance betulinic acid production from betulin catalysed by fungus Armillaria luteo‐virens Sacc ZJUQH100‐6. Methods and Results: Fractional factorial design and response surface methodology were applied to optimize the main parameters that affect betulinic acid production in the growing‐cells system. Results indicated that the addition of Tween 80 and substrate concentration were identified as the significant factors on betulinic acid formation, and the central composite experimental design was then adopted to derive a statistical model for optimizing biotransformation conditions. The optimum conditions were observed at pH 6·0, 0·57% Tween 80, 15 mg l−1 betulin and at 3 days of stage of inoculation. Conclusions: Under the optimized conditions, the highest productivity of betulinic acid predicted was 9·32%, which increased by 74·53% in comparison with that of the nonoptimized. The verified experiment revealed that the model can well simulate betulin biotransformation. Moreover, the bioconversion of betulin and betulin‐28‐monooxygenase activities was compared between the optimized and the nonoptimized conditions. Significance and Impact of the Study: Current data imply that betulinic acid production from betulin can be effectively enhanced through biotransformation optimization strategy.

An efficient process for the transformation of betulin to betulinic acid by a strain of Bacillus megaterium

“…Three factor temperature, pH and substrate concentration were selected according to statistical design and available literature for biotransformation of betulin (Dubey et al 2008;Liu et al 2011). The interaction effect in among these parameters (temperature 25-35°C, pH 5.25-7.25, and betulin concentration 0.9-6 g/l) and their roles in transformation of betulin were determined by RSM.…”

“…The microbial consortiums capable of growing under betulin stress were grown by enrichment culture in 250 ml flask similarly as followed by other researchers (Liu et al 2011;Mao et al 2012;Grishko et al 2013). Initially isolated microbes were exposed for 05 weeks at 1 g/l betulin stress and then stable colonies as the resistant isolates were obtained after 6 weeks.…”

“…Gradient mobile phase consisting of ethyl acetate and hexane with 7:3 ratios was used for elution of betulinic acid (Chatterjee et al 2000). The eluent was tested by HPLC at 1.0 ml/min flow rate and with 210 nm wavelength at room temperature (Liu et al 2011;Feng et al 2013). For getting crystals of betulinic acid, the elute was mixed twice the volume of elute with the mixture of ethyl acetate and methanol (9:1) and is kept at 4 ± 1°C overnight.…”

“…While in another report, under optimum conditions Rhodotorula mucilaginosa transformed 52.65% betulin to two products out of which one was detected as betulone (Mao et al 2012). Another group of researchers investigated betulin transformation to betulinic acid using Armillaria luteovirens Sacc-QH with *9.32% maximum productivity of betulinic acid under optimized environment (Liu et al 2011). The growing cells of Rhodococcus rhodochrous IEGM 66 transformed 0.50 g/l betulin to betulone with 45% conversion rate within 240 h (Grishko et al 2013).…”

“…Besides that, biotransformation methods are more stereo-and regio-selective. Including that few reactions that cannot be easily completed thorough chemical approaches are performed by microbial transformation in an easier way (Pervaiz et al 2013;Bastos et al 2007;Liu et al 2011;Mao et al 2012;Feng et al 2013;Chen et al 2008;Shao et al 2016). Cunninghamella blakesleeana has also been investigated for biotransformation of betulin to betulinic acid analyzed by HPLC (Feng et al 2013).…”